Aflatoxin M1 in raw and ultra high temperature-treated milk commercialized in Portugal.

During June to September 1999, 31 samples of raw milk were obtained from individual farms and 70 samples of ultrahigh-temperature-treated (UHT) milk (18 samples of whole milk, 22 of semi-skimmed and 30 samples of skimmed milk) were collected in supermarkets in Lisbon, Portugal. The total number of samples analysed was 101. The incidence of aflatoxin M1 (AFM1) contamination in the milk samples analysed was very high (83.2%). AFM1 was detected in 80.6% of raw milk and 84.2% of UHT milk. Concerning raw milk, 17 samples (54.8%) contained low levels (0.005-0.010 microgram/l), two samples (6.5%) had levels ranging from 0.011 to 0.020 microgram/l and six samples (19.3%) had levels between 0.021 and 0.050 microgram/l. Of 70 samples of UHT milk analysed, 10 samples had levels below 0.005 microgram/l (one whole milk, two semi-skimmed milk and seven skimmed milk). Nine samples--two whole milk (11.1%) and seven skimmed milk (23.3%)--were contaminated with levels between 0.005 and 0.010 microgram/l. Twenty-five samples (eight whole milk, 44.4%; one semi-skimmed milk, 4.5%; and 16 skimmed milk, 53.4%) had AFM1 contamination levels of 0.011-0.020 microgram/l. Six samples of whole milk (33.3%) and 18 samples of semi-skimmed milk (81.9%) had levels of 0.021-0.050 microgram/l. Only two samples were contaminated at levels above the legal limit for AFM1 (one whole milk and one semi-skimmed milk, 0.059 and 0.061 microgram/l, respectively). At the moment, the contamination of milk with AFM1 does not appear to be a risk to public health, although the presence of this toxin was detected in 83.2% of the samples analysed.